When a vehicle is serviced it is usually located within a private garage, a service station or a multi-bay facility at an automotive dealership. Although many service functions are performed while the vehicle is not running it is not possible to effectively tune the vehicle's engine without running the engine at various speeds. Such operation results, of course, in the creation of exhaust and it is necessary to therefore ensure that the exhaust is removed from the confines of the service facility to avoid the harmful effects of carbon monoxide contained in the exhaust gases.
In the past many service facilities have connected a long flexible hose to the end of the vehicle's exhaust pipe with the hose then being led outside the service facility, perhaps under or though a roll-up garage door. This arrangement is quick and easy to use but it is not an optimal solution to the problem because there can be considerable leakage past the hose end where it is connected to the vehicle's exhaust pipe, especially if there is not a close match of hose and pipe diameters. Different manufacturers often utilize different diameter exhaust pipes and each service facility will be reluctant to stock exhaust extraction hoses of different sizes just to accommodate these various exhaust pipe diameters. A hose which fits tightly on the largest exhaust pipe will fit loosely on the smallest pipe, whereas a hose that fits tightly on the smallest pipe will probably not stretch sufficiently to fit the largest pipe. The first condition results in leakage whereas the second condition means that several sizes of exhaust hose will be needed to fit all sizes of exhaust pipe.
An obvious solution to this problem is a coupler that can fit over the end of an exhaust pipe, no matter what its diameter might be, and will then connect to an exhaust hose of an appropriate diameter. Such a coupler should obviate the problems discussed above.
One attempt at providing such a coupler is found in U.S. Pat. No. 4,779,904 of Oct. 25, 1988. That patent teaches a coupler having means for connection to exhaust hoses of different sizes and an assembly of radially inwardly directed nylon bristles which are intended to provide a seal around an exhaust pipe. The bristles are deflected rearwardly when the unit is placed over the exhaust pipe and the unit should accommodate any size of exhaust pipe. During use, however, the bristles tend to become brittle and worn and they lose very quickly their ability to seal the coupler to the exhaust pipe.
Another problem which must now be addressed, and which is not solved by the '904 coupler, is the recent mandated requirement that service facilities provide an automatic powered system which draws exhaust fumes by vacuum, through filtration equipment to the outside environment. With such a system the exhaust hoses are connected to the vacuum equipment which in turn filters and then exhausts the filtered gases to the atmosphere. With the '904 coupler in place, and assuming proper operation, the utilization of automatic vacuum systems could have a deleterious effect on the engine adjustments since the engine would not be performing at standard operating conditions, the exhaust being extracted under vacuum rather than exiting normally to the atmosphere.